The study of migraine has yielded many benefits for headache patients. Little research, however, has been performed on refractory migraine (RM) headache, a term often used interchangeably with intractable migraine. This may be a consequence of a lack of a well-accepted definition. In a survey performed by the Refractory Headache Special Interest Section (RHSIS) on the American Headache Society (AHS) in 2006, 58% of the members agreed that a definition for refractory headache should be added to the International Classification of Headache Disorders-2. A PubMed search identified 21 articles that defined refractory or intractable headache/migraine. Sixteen (76%) defined the term “refractory” and 5 (24%) defined the term “intractable.” Many of these definitions did not address the need for an adequate trial of a preventive medicine, disability, and medication overuse. An operational definition will allow us to better characterize the disorder, address unmet medical needs, and identify the most effective treatments. RHSIS of the AHS has proposed a definition of RM. It is our hope that this definition will spur interest in this entity and will lead to further research in the area.